Active Telemetry Response for Hearing Implants

ABSTRACT

An implantable processor arrangement is described for an active implantable medical device (AIMD) system implanted under the skin of a patient. An implantable communications coil arrangement is configured for transdermal transfer of an implant communications signal. An implantable processor is coupled to and controls the implantable communications coil arrangement so as to operate in two different communications modes. In a normal operation mode, the processor configures the communications coil arrangement for peridermal communication with an external communications coil placed on the skin of the patient immediately over the implantable communications coil arrangement using load modulation of the communications coil arrangement, wherein the implantable communications coil has a resonance frequency matching the transmission frequency. In a long range telemetry mode, the processor configures the communications coil arrangement for extradermal communication with an external telemetry coil located distant from the skin of the patient immediately over the implantable communications coil arrangement.

This application is a divisional of co-pending U.S. patent applicationSer. No. 15/103,365, filed Jun. 10, 2016, which in turn is a nationalphase entry of Patent Cooperation Treaty Application PCT/US2014/071063,filed Dec. 18, 2014, which in turn claims priority from U.S. ProvisionalPatent Application 61/918,911, filed Dec. 20, 2013, all of which areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to active implantable medical device(AIMD) systems for example neuro stimulation devices and withoutlimitation such as cochlear implants, laryngeal or heart pacemakers, andmore specifically to telemetry communication in such systems.

BACKGROUND ART

In some AIMD systems such as commercially available cochlear implantsystems, Spinal Cord Stimulator (SCS) systems, all of the datacommunications and power supply requirements are met via a closetranscutaneous arrangement with an external transmission coil placed onthe skin directly over the implanted receiver coil such as described,for example, in U.S. Patent Publication 2012/0109256, which isincorporated herein by reference in its entirety. In other types of AIMDsystems such as Implantable Cardiac Defibrillators (ICD) and HeartPacemakers (PM) have primary galvanic cells as power source and fortelemetry purposes use either a coil arrangement as described above, orelse an RF link in the Medical Implant Communication Service (MICS)frequency band (402 to 405 MHz) that requires a separate IC and amatched antenna (coil). For the sole purpose of data transfer, MICStransceivers are more compact than an inductive coil system and thesedevices work at a distance of up to 2 m and so can be utilized in thesurgical operating theatre. A major task is to keep the powerconsumption of the device small so that the overall lifetime of animplant with a primary cell is not significantly reduced.

In AIMD systems that use an inductive communication coil arrangement,telemetry data from the implanted components back across the skin to theoutside is typically performed using load modulation of the receivercoil arrangement to modulate the load on the external transmitter coil.That requires the external coil to be in close vicinity to the implantedcoil, which during implantation surgery can only be achieved if theexternal coil is placed in a sterile package and is then positionedclose to the open surgical wound. That limits the freedom of thephysician/surgeon to manipulate the implant, e.g. optimizing the implantor electrode position while the implant is operating.

One typical example of an AIMD system is a cochlear implant. A normalear transmits sounds as shown in FIG. 1 through the outer ear 101 to thetympanic membrane (eardrum) 102, which moves the bones of the middle ear103, which in turn vibrate the oval window and round window openings ofthe cochlea 104. The cochlea 104 is a long narrow duct wound spirallyabout its axis for approximately two and a half turns. The cochlea 104includes an upper channel known as the scala vestibuli and a lowerchannel known as the scala tympani, which are connected by the cochlearduct. The scala tympani forms an upright spiraling cone with a centercalled the modiolar where the spiral ganglion cells of the acousticnerve 113 reside. In response to received sounds transmitted by themiddle ear 103, the fluid filled cochlea 104 functions as a transducerto generate electric pulses that are transmitted to the cochlear nerve113, and ultimately to the brain. Hearing is impaired when there areproblems in the ability to transduce external sounds into meaningfulaction potentials along the neural substrate of the cochlea 104.

In some cases of hearing impairment, a cochlear implant AIMD system maybe provided that electrically stimulates auditory nerve tissue withsmall currents delivered by multiple electrode contacts distributedalong an implant electrode. FIG. 1 shows some components of a typicalcochlear implant system where an external microphone provides an audiosignal input to an external signal processor 111 which implements one ofvarious known signal processing schemes. The processed signal isconverted by the external signal processor 111 into a digital dataformat, such as a sequence of data frames, for transmission by anexternal transmitter coil 107 across the skin into a receiver processorin a stimulator processor 108. The stimulator processor 108 extracts theaudio information in the received signal and also a power component thatprovides electrical power for the implanted parts of the system. Thereceiver processor in the stimulator processor 108 may performadditional signal processing such as error correction, pulse formation,etc., and produces a stimulation pattern (based on the extracted audioinformation) that is sent through connected wires 109 to an implantelectrode 110. Typically, the implant electrode 110 includes multipleelectrodes 112 on its surface that provide selective stimulation of thecochlea 104.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to an implantableprocessor arrangement for an AIMD system implanted under the skin of apatient; e.g., a cochlear implant system. An implantable communicationscoil arrangement is configured for transdermal transfer of an implantcommunications signal. An implantable processor is coupled to andcontrols the implantable communications coil arrangement so as tooperate in two different communications modes. In a normal operationmode the processor configures the communications coil arrangement forperidermal communication with an external communications coil placed onor close to the skin of the patient immediately over the implantablecommunications coil arrangement using load modulation of thecommunications coil arrangement, wherein the implantable communicationscoil has a resonance frequency matching the transmission frequency. In along range telemetry mode the processor configures the communicationscoil arrangement for extradermal communication with an externaltelemetry coil located distant from the skin of the patient immediatelyover the implantable communications coil arrangement.

Embodiments of the present invention also include a fitting system foran AIMD system; e.g., a cochlear implant system. An external fittingmodule is configured to perform a patient fitting process that adjustsan implanted AIMD processor to reflect patient-specific performancecharacteristics. The AIMD processor controls two differentcommunications modes. In a normal operation mode the processorconfigures an implanted communications coil arrangement for peridermalcommunication of an implant communications signal with an externalcommunications coil placed on the skin of the implanted patientimmediately over the implanted communications coil arrangement fornormal operation of the AIMD system, using load modulation of thecommunications coil arrangement, wherein the implantable communicationscoil has a resonance frequency matching the transmission frequency. In along range telemetry mode the processor configures the implantedcommunications coil arrangement for extradermal communication with anexternal telemetry coil located distant from the skin of the implantedpatient immediately over the implantable communications coilarrangement. And the patient fitting process includes interaction of theexternal fitting module via the external telemetry coil with the AIMDprocessor in the long range telemetry mode to adjust the operation ofthe AIMD processor in the normal operation mode based on thepatient-specific performance characteristics.

Embodiments of the present invention also include a testing system foruse during surgical implantation of an AIMD system; e.g., a cochlearimplant system. An implantable communications coil arrangement isconfigured for transdermal transfer of an implant communications signal.An implantable processor is coupled to and controls the implantablecommunications coil arrangement so as to operate in two differentcommunications modes. In a normal operation mode, the processorconfigures the communications coil arrangement for peridermalcommunication with an external communications coil placed on the skin ofthe implanted patient immediately over the implantable communicationscoil arrangement using load modulation of the communications coilarrangement, wherein the implantable communications coil has a resonancefrequency matching the transmission frequency. In a long range telemetrymode, the processor configures the communications coil arrangement forextradermal communication with an external telemetry coil locateddistant from the skin of the implanted patient immediately over theimplantable communications coil arrangement.

In specific embodiments of any of the foregoing, the extradermalcommunication in the long range telemetry mode may include communicationof an implant programming signal received by the implantablecommunications coil arrangement, and/or an implant telemetry signaltransmitted by the implantable communications coil arrangement. Theimplantable processor may control operation in the long range telemetrymode to be limited in initiation to periodic intervals, and/or bysoftware control during a defined wake-up procedure.

There may be one or more coupling capacitors configured to allow aDC-free coupling of the communications coil arrangement with a datadriving circuit for the implantable processor. For example, thecommunications coil arrangement may include a resonant tank circuit witha tank capacitance and a resonance frequency, wherein in the long rangetelemetry mode the tank capacitance and the one or more couplingcapacitors are coupled together in with a series capacitance below theresonance frequency of the resonant tank circuit when in the normaloperation mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows anatomical features of a typical human ear having acochlear implant system.

FIG. 2 shows an example of circuit components in one specific embodimentof the present invention.

FIG. 3 shows the product of the coil current and transmission carrierfrequency normalized by the resonance frequency f₀ of the tank circuitin one specific embodiment of the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

In AIMD systems which include a signal receiver coil, e.g. forrecharging an implant battery, that battery can be used by the implantedprocessor as a power source to produce an alternating magnetic fieldutilizing the implant coil. The produced field can be modulated anddetected by an external coil that can be distant from the skinimmediately over the implant. Thus embodiments of the present inventionare directed an AIMD system that operates an implanted active drivencircuit L-C transmitter using existing load-modulation components. Sothe parallel or serial L-C resonance circuit that is normally availablefor load modulation or energy transfer to the implant is used for signaltransmission beyond the peridermal region near the skin covering theimplant. This makes efficient use of already available existing elementsfrom the load modulator to solve the problem of a long-distance backtelemetry RF-link that is not achievable by conventionalload-modulation. Besides the implanted system components as such,embodiments also include a testing system for use during surgicalimplantation of an AIMD system which includes an implantable processorhaving such an active telemetry response mode, as well as apost-surgical fitting system for patient-specific fitting of an AIMDsystem having such an active telemetry response mode.

FIG. 2 shows specific circuit components of one embodiment of such animplantable processor arrangement for an AIMD system implanted under theskin of a patient. An implantable communications coil arrangement isconfigured for transdermal transfer of an implant communications signal.An implantable processor CPU1 is coupled to and controls the implantablecommunications coil arrangement that includes parallel tank circuitL1-C1 so as to operate in two different communications modes. AlthoughL1-C1 in FIG. 2 is shown as a parallel tank circuit, it is understoodthat a series tank circuit L1-C1 may be equivalently used.

In a normal operation mod, the processor CPU1 configures thecommunications coil arrangement for conventional peridermalcommunication to receive signals transmitted by an externalcommunications coil placed on the skin of the patient immediately overthe implanted L1 coil of the communications coil arrangement. Paralleltank L1-C1 has a resonance frequency that is preferably the same as thefrequency of the communications signal transmitted by the external coil.The received signal developed by L1-C1 is rectified by CR1 and passesthrough closed switch S4 over filtering capacitor C4 to power regulatorPR1, which charges the implant battery B1. The data component of thereceived signal is picked up at L1-C1 and capacitively coupled to anconventional known receiver module (not shown, e.g. anenvelope-detector) connected to the implant processor CPU1 whichdevelops the stimulation signals for output to the other implantedcomponents such as to the stimulation contacts on a cochlear implantelectrode array. The receiver may be realized by closing switch S5 andutilizing Amplifier A2. The remaining control switches S2 and S3 areopen in the normal operations mode to remove their associated componentsfrom operation of the implant. In one embodiment, control switch S1 andload resistor R1 are implemented to provide conventional loadmodulation-based telemetry functionality. In a further embodiment, theconventional load modulation-based telemetry function is implementedwith capacitor C2 and switch S2. This has the further advantage thatthen there is no need to have the load resistor R1 and switch S1, butonly capacitor C2 and switch S2 are needed. To lower power consumption,data driver A1 and/or low noise amplifier A2 may be disabled.

In a long range telemetry mode, the implant processor CPU1 configuresthe communications coil arrangement—the resonant tank L1-C1—forextradermal communication with an external telemetry coil located beyondthe skin of the patient immediately over the implanted coil. But thelong-range mode has no conventional load-modulation functionality.Control switches S1, S4 and S5 are opened and control switches S3 and S2are closed so that the implant processor CPU1 sends outbound telemetrydata to a data driver A1, which modulates that outbound telemetry datasignal at the resonance frequency (the carrier frequency) of theresonant tank L1-C1 which creates a modulated and alternating magneticfield that is extradermally transmitted across the skin to telemetryreceiver components beyond the peridermal near skin region; for example,1-2 meters across a surgical operating theater. Coupling capacitors C2and C3 allow a DC-free coupling of the resonance tank L1-C1 with thedata driving circuit.

To receive data, control switch S3 is opened, removing data driver A1from the circuit, and control switch S5 is closed adding low noiseamplifier A2 that amplifies and provides the received long-range datasignal from the resonant tank L1-C1 to the implant processor CPU1. Thedata driver A1 may be disabled to reduce power consumption.

The extradermal mode has the disadvantage of increased power consumptionof the implanted components. To mitigate this problem, the extradermalmode may be enabled only when needed, e.g. by periodic short-termedsniffing or a special wakeup-procedure, which may be implemented withappropriate software processes. And it should be understood the powersupply components in the implanted arrangement are not limitedspecifically to a battery as such, and include without limitation moregeneral energy storage such as a storage capacitor suitable for actingas a temporary power supply when in the extradermal mode. Such a storagecapacitor could be configured to provide power only during short periodsin the extradermal mode when data bursts are transmitted from the AIMD,and then the storage capacitor can be recharged by the receivedcommunications signal during the longer periods in between. In addition,an implant system typically does not start sending telemetry data on itsown, but rather does so only in response to one or more specificcommands from an external device, such that the system as a whole worksin a type of master-slave mode. This is useful since the implanted powersource has a limited lifetime and a limited capacity so care is taken tonot waste the available energy.

During extradermal mode transmission, the power efficiency of the datatransmitting components of the AIMD may be improved by optimizing thecapacitances C2 and C3. Both capacitances C2 and C3 can be representedby series capacitance 23=C2·C3/(C2+C3). The series capacitance is thenchosen such that the resonance peak is at a lower frequency than theresonance frequency of the tank circuit L1-C1 atf₀₌1/(2·π)·(L1·C1)^(−1/2); thereby maximizing the rms current I_(L1)through the coil L1. That may increase the coil current by a factor of 2or more for the same driving strength (i.e. peak-peak-voltage) deliveredby data driver A1. This yields a better detection performance (e.g.induced voltage in the receiver-coil) and/or increased range. On theother hand, if detection performance and range is kept constant, thisimprovement reduces power consumption, for example by reducingpeak-peak-voltage delivered from and/or supply voltage for data driverA1. At the receiver coil, the induced voltage not only relies on thetransmitter e.g. I_(L1) coil current, but also is proportional to thetransmission carrier frequency. Hence, the product of the implant coilcurrent and the actual transmission frequency is needed for aquantitative evaluation of the quality.

FIG. 3 shows the product of the coil current and transmission carrierfrequency normalized by the resonance frequency f₀ of the tank circuitL1-C1 for L1=10 μH and C1=25.3 nF with 5Ω coil resistance and forexample with C23=50 nF and C23 _(mod)=10 nF as function of thetransmission carrier frequency f. In both examples, the resonance peakis below the resonance frequency f₀ with 48 mA at 85 kHz and 77 mA at 58kHz, respectively. This corresponds to an effective increase of 200% and380% of the voltage induced in the receiver coil.

As just explained, the data transmitting components of the AIMD consumepower only during the actual transmission period, but the receivingcomponents need to be enabled and powered over a longer time. Dependingon its sensitivity to the received input signal, an AIMD receiver canconsume a significant amount of the overall implant power. One way toaddress that consideration is to define a wakeup-procedure which onlyactivates the AIMD receiver for a short time span within a long timeinterval; e.g. for 1 millisecond every 1 second, an effective load of 1permille. If no wakeup-signal is detected during the activationinterval, the AIMD receiver is set into a power-saving mode and againreactivated a second later. If a wakeup-signal is detected, then theAIMD receiver may remain active for a defined extradermal mode intervaldepending on the received data and commands, with the additionalconstrain that the receiver also may be powered down while the implantedtransmitter arrangement is sending back telemetry data.

So depending on the implant function, the AIMD receiver may only beactive within a limited specific time span. Extradermal mode data can betransmitted to the external device which then only sends incoming datawithin the given active time span (this may also include a new wake up).Outside this defined active receive time span the AIMD receiver may becompletely shut down without sniffing to conserve a maximum amount ofpower in the implant. Such extradermal mode data may include a receiverstrength signal indicator (RSSI) for each communication partner toindicate to the relevant sender if its transmitted signal is strongenough to be effective, or if it has to be increased, or it may even bedecreased to save power.

To enable the extradermal mode, the external programming device may sendan extradermal mode request command to the AIMD client andsimultaneously start a timer. Upon reception of the command by the AIMDclient (either the audio processor or the AIMD implant itself) the AIMDclient transmits an acknowledge command to the external programmingdevice using the extradermal link. If the external programming devicereceives the acknowledgement command while the timer is still running,the extradermal mode link is considered established. The transmissionpower of the external programming device can be set to a lower levelthan the one used by the AIMD client to ensure that the programmingdevice receives the acknowledgement. The power level may bepredetermined in both the external programming device and the AIMDclient, or the external programming device may be able to select anoperating power level. In the latter case, the extradermal mode requestcommand may include a power level value used for transmission by theexternal programming device such that the AIMD client can read the powerlevel value and use it to set its transmission power for extradermalmode transmission such as for the acknowledgement signal. For example,the AIMD client may use the same power level used by the externalprogramming device, or it may increase that power level by apre-determined amount. This dynamic transmission power negotiation hasthe advantage to set the AIMD client power level to the smallest neededfor reliable extradermal mode communication.

This power level negotiation procedure can be repeated at any timeduring operation in extradermal mode to dynamically adjust the powerneeded. For example, the external programming device may issue a powerlevel command periodically, or based on the measured reception signallevel or signal quality of the back-telemetry signal. The signal levelmay be a reception power level value, and/or the signal quality may be asignal to noise ratio (SNR).

To terminate an extradermal mode session, the AIMD client may have atimeout such that when no commands are received for some defined periodof time, the AIMD client disables the extradermal mode (e.g., andreturns to peridermal mode operation). Or the external programmingdevice may transmit a normal mode request command, which the AIMD clientresponds to by transmitting an acknowledgement in to the externalprogramming device using the extradermal link and then enters normalrange peridermal mode. Of course specific embodiments may include otherfunctions and features such as for information security and/or sessioncontrol. Such additional features can be added, for example, within orafter the wake up procedure.

The extradermal mode eases surgical handling when the implant is tested,and avoids the need to bring the external transmitter coil into closeproximity to the wound opening at the patient which has to be keptsterile. Thus conventionally the external transmitter coil has to besterilized (or placed into a sterile package) before bringing it intoclose proximity to the patient. But that is no longer necessary with thelonger-distance extradermal mode of operation.

Besides testing during implantation surgery, the extradermal mode alsomay be useful during post-surgical patient fitting sessions. In thatcase, an external fitting module issues a command to switch the implantprocessor into the extradermal mode to back telemetry signals for thefitting. This enhances patient comfort during the fitting because nohard cabling is needed.

Some embodiments may also support providing the patient with a remotecontrol to engage the extradermal mode to allow an easy check of theimplant state (e.g., battery state) or to change some system settings(on/off, different parameter settings). Moreover, using the extradermalmode of operation the implant system also may communicate with a homemonitoring system to transfer log data (as is done for heartpacemakers).

Compared to conventional load modulation telemetry arrangements, littleadditional circuitry is needed, and an operating frequency band forimplant telemetry functions is available worldwide (9 to 315 kHz). Thecommunication coil in the external programming device may need to berelatively large (e.g. more than 10 cm in diameter) and the effectiveoperating distance between external device and internal implant coil maystill be rather limited (e.g., 2 meters or less—within the sterilesurgical area). But for post-surgical fitting sessions outside thesurgical operating theatre, the physician or audiologist may simplyplace the external communication coil on his desk facing it towards thepatient and need not locate the exact position of the implant.

Embodiments of the invention may be implemented in part in anyconventional computer programming language. For example, preferredembodiments may be implemented in a procedural programming language(e.g., “C”) or an object oriented programming language (e.g., “C++”,Python). Alternative embodiments of the invention may be implemented aspre-programmed hardware elements, other related components, or as acombination of hardware and software components.

Embodiments also can be implemented in part as a computer programproduct for use with a computer system. Such implementation may includea series of computer instructions fixed either on a tangible medium,such as a computer readable medium (e.g., a diskette, CD-ROM, ROM, orfixed disk) or transmittable to a computer system, via a modem or otherinterface device, such as a communications adapter connected to anetwork over a medium. The medium may be either a tangible medium (e.g.,optical or analog communications lines) or a medium implemented withwireless techniques (e.g., microwave, infrared or other transmissiontechniques). The series of computer instructions embodies all or part ofthe functionality previously described herein with respect to thesystem. Those skilled in the art should appreciate that such computerinstructions can be written in a number of programming languages for usewith many computer architectures or operating systems. Furthermore, suchinstructions may be stored in any memory device, such as semiconductor,magnetic, optical or other memory devices, and may be transmitted usingany communications technology, such as optical, infrared, microwave, orother transmission technologies. It is expected that such a computerprogram product may be distributed as a removable medium withaccompanying printed or electronic documentation (e.g., shrink wrappedsoftware), preloaded with a computer system (e.g., on system ROM orfixed disk), or distributed from a server or electronic bulletin boardover the network (e.g., the Internet or World Wide Web). Of course, someembodiments of the invention may be implemented as a combination of bothsoftware (e.g., a computer program product) and hardware. Still otherembodiments of the invention are implemented as entirely hardware, orentirely software (e.g., a computer program product).

Embodiments of the present invention may be implemented in variousspecific AIMD systems, such as, without limitation, cochlear implantsystems, totally implantable cochlear implant systems, vestibularimplant systems, laryngeal pacemaker systems, middle ear implant systemsand bone conduction implant systems. The invention is equally applicablein the external components of these systems or in the implantedcomponents of these systems. Although various exemplary embodiments ofthe invention have been disclosed, it should be apparent to thoseskilled in the art that various changes and modifications can be madewhich will achieve some of the advantages of the invention withoutdeparting from the true scope of the invention.

What is claimed is:
 1. An implantable processor arrangement for anactive implantable medical device (AIMD) system implanted under the skinof a patient, the arrangement comprising: an implantable communicationscoil arrangement configured for transdermal transfer of an implantcommunications signal at a given transmission frequency; and animplantable processor coupled to and controlling the implantablecommunications coil arrangement so as to operate in two differentcommunications modes: i. a normal operation mode wherein the processorconfigures the communications coil arrangement for peridermalcommunication with an external communications coil placed on the skin ofthe patient immediately over the implantable communications coilarrangement using load modulation of the communications coilarrangement, wherein the implantable communications coil has a resonancefrequency matching the transmission frequency, and ii. a long rangetelemetry mode wherein the processor configures the communications coilarrangement for extradermal communication with an external telemetrycoil located distant from the skin of the patient immediately over theimplantable communications coil arrangement.
 2. The arrangementaccording to claim 1, further comprising: one or more couplingcapacitors configured to allow a DC-free coupling of the communicationscoil arrangement with a data driving circuit for the implantableprocessor.
 3. The arrangement according to claim 2, wherein thecommunications coil arrangement includes a resonant tank circuit with atank capacitance and a resonance frequency, wherein in the long rangetelemetry mode the tank capacitance and the one or more couplingcapacitors are coupled together in with a series capacitance below theresonance frequency of the resonant tank circuit when in the normaloperation mode.
 4. The arrangement according to claim 1, wherein theextradermal communication in the long range telemetry mode includescommunication of an implant programming signal received by theimplantable communications coil arrangement.
 5. The arrangementaccording to claim 1, wherein the extradermal communication in the longrange telemetry mode includes communication of an implant telemetrysignal transmitted by the implantable communications coil arrangement.6. The arrangement according to claim 1, wherein the implantableprocessor controls operation in the long range telemetry mode to belimited in initiation to periodic intervals.
 7. The arrangementaccording to claim 1, wherein the implantable processor controlsoperation in the long range telemetry mode to be limited in initiationby software control during a defined wake-up procedure.
 8. Thearrangement according to claim 1, wherein the AIMD system is a cochlearimplant system.
 9. A fitting system for an active implantable medicaldevice (AIMD) system, the fitting system comprising: an external fittingmodule configured to perform a patient fitting process that adjusts animplanted AIMD processor to reflect patient-specific performancecharacteristics, wherein the AIMD processor has: i. a normal operationmode wherein the processor configures the communications coilarrangement for peridermal communication with an external communicationscoil placed on the skin of the patient immediately over the implantablecommunications coil arrangement using load modulation of thecommunications coil arrangement, wherein the implantable communicationscoil has a resonance frequency matching the transmission frequency, andii. a long range telemetry mode that configures the implantedcommunications coil arrangement for extradermal communication with anexternal telemetry coil located distant from the skin of the implantedpatient immediately over the implantable communications coilarrangement; and wherein the patient fitting process includesinteraction of the external fitting module via the external telemetrycoil with the AIMD processor in the long range telemetry mode to adjustthe operation of the AIMD processor in the normal operation mode basedon the patient-specific performance characteristics.
 10. The systemaccording to claim 9, further comprising: one or more couplingcapacitors configured to allow a DC-free coupling of the communicationscoil arrangement with a data driving circuit for the implantableprocessor.
 11. The system according to claim 10, wherein thecommunications coil arrangement includes a resonant tank circuit with atank capacitance and a resonance frequency, wherein in the long rangetelemetry mode the tank capacitance and the one or more couplingcapacitors are coupled together in with a series capacitance below theresonance frequency of the resonant tank circuit when in the normaloperation mode.
 12. The system according to claim 9, wherein theextradermal communication in the long range telemetry mode includescommunication of an implant programming signal received by the implantedcommunications coil system.
 13. The system according to claim 9, whereinthe extradermal communication in the long range telemetry mode includescommunication of an implant telemetry signal transmitted by theimplanted communications coil system.
 14. The system according to claim9, wherein the AIMD processor controls operation in the long rangetelemetry mode to be limited in initiation to periodic intervals. 15.The system according to claim 9, wherein the AIMD processor controlsoperation in the long range telemetry mode to be limited in initiationby software control during a defined wake-up procedure.
 16. The systemaccording to claim 9, wherein the AIMD system is a cochlear implantsystem.